States Extend RSV Immunization Period Amidst Continued Spread
Respiratory syncytial virus has continued to circulate later into the spring this year. As a result, many jurisdictions adjusted their immunization windows for eligible infants and toddlers.
Federal testing data for the third week of March showed a 7.5% RSV test positivity rate. That rate exceeded last year’s 5% level at the same time.
Expanding the immunization window
In mid-March, the CDC urged states to review local RSV trends. Public health officials responded by allowing additional months of monoclonal antibody administration.
The Association of Immunization Managers coordinated with 66 federally funded immunization programs. By the most recent count, 48 jurisdictions extended their season through at least April 30.
Formal extensions permit jurisdictions to order shots through the Vaccines for Children program for one more month. The changes also encourage providers to keep administering immunizations while activity stays elevated.
Jurisdictional differences
Ten areas, including Florida, Hawaii and Oregon, report year-round RSV surveillance or data that did not support an extension. Louisiana and Washington, D.C., chose not to extend the period.
Missouri and Virginia are handling additional orders on a case‑by‑case basis. Washington state saw RSV activity rise in December, more than a month later than usual.
Protection options and evidence
Monoclonal antibodies are recommended to prevent RSV in infants and some young children. The American Academy of Pediatrics supports their use for eligible patients.
A vaccine is also available for pregnant people to provide maternal protection. Monoclonal antibodies provide passive immunity and have delivered measurable reductions in hospitalizations.
- CDC data show two to three out of every 100 infants younger than three months are hospitalized with RSV each year.
- Health officials report tens of thousands of pediatric hospitalizations this season.
- A CDC study found lower RSV hospitalization rates among infants up to seven months during the 2024–25 season, versus earlier seasons.
Regulatory and program notes
This marks the third season that monoclonal antibodies have been available for RSV protection. HHS maintained its guidance that infants whose mothers did not receive the vaccine should get an antibody dose.
State and federal regulators continue reviews of the RSV shots, even though safety and effectiveness have been documented. Public health programs are balancing surveillance, supply, and provider guidance.
Why the season shifted
Experts do not have a single explanation for the later peak. Possible drivers include environmental, biological and behavioral factors.
Changes in when people seek care or seasonal climate shifts may have influenced transmission. Officials emphasize that responses should follow real‑time disease trends, not a fixed calendar.
Keeping RSV monoclonal antibodies available while the virus circulates remains a priority for many health departments. States extend RSV immunization period in order to match protection to current disease activity.
Public health leaders say an extra month can have a meaningful impact. With roughly 10,000 births daily in the United States, officials stress continued efforts to prevent infant RSV hospitalizations.
Reporting and analysis for Filmogaz.com.
